Complete Genome Sequences of Two Phage-Like Plasmids Carrying the CTX-M-15 Extended-Spectrum β-Lactamase Gene

Area of Science:

• Microbiology
• Genetics
• Molecular Biology

Background:

• Antimicrobial resistance is a growing global health concern.
• CTX-M-15 is a prevalent extended-spectrum beta-lactamase (ESBL) conferring resistance to crucial antibiotics.
• Plasmids are key mobile genetic elements facilitating the spread of antimicrobial resistance genes.

Purpose of the Study:

• To characterize novel phage-like plasmids carrying CTX-M-15 from environmental Escherichia coli isolates.
• To investigate the genetic relatedness of these plasmids to previously identified plasmids and bacteriophages.

Main Methods:

• Isolation and identification of Escherichia coli from environmental samples.
• Plasmid DNA extraction and sequencing.
• Bioinformatic analysis to determine nucleotide sequence identity and phylogenetic relationships.

Main Results:

• Two environmental Escherichia coli isolates harbored similar phage-like plasmids.
• These plasmids carried CTX-M-15 resistance cassettes.
• Strong nucleotide sequence identity was observed between the identified plasmids and the known phage-like plasmid pECOH89 and Salmonella bacteriophage SSU5.

Conclusions:

• Environmental Escherichia coli can carry and disseminate CTX-M-15 through novel phage-like plasmids.
• The genetic similarity to pECOH89 and Salmonella bacteriophage SSU5 suggests potential horizontal gene transfer mechanisms.
• These findings highlight the importance of environmental surveillance for tracking antimicrobial resistance dissemination.